1. Field of the Invention
The present invention relates to electrical connectors and particularly to a low insertion force type connector and electrical contact therefor which are to be electrically connected to a printed circuit board.
2. Description of the Related Art
Examples of prior art low insertion force type electrical connectors for printed circuit boards are disclosed in U.S. Pat. No. 4,575,172 issued Mar. 11, 1986 and U.S. Pat. No. 4,737,120 issued Apr. 12, 1988. A sectional view of the connector of U.S. Pat. No. 4,575,172 is schematically illustrated in FIG. 1 while a similar view of the connector of the U.S. Pat. No. 4,737,120 is shown in FIG. 2. Both are of the type wherein a printed circuit board 15 is inserted into the connector and vertically held in proper place.
The prior art connector shown in FIG. 1 has a pair of curved spring members 16 with their contact portions offset relative to each other. Since the spring members are formed from the same short bar, they do not provide adequate flexibility when a printed circuit board is inserted into the connector. In order to improve the flexibility of these spring members sufficiently, it would be necessary to make them much thinner. Too thin a spring member, however, may not have the necessary mechanical strength.
The prior art connector shown in FIG. 2 employs a lengthy, meandering spring 16 in comparison with the short spring members shown in FIG. 1. Since, however, the distance between the pivot points and the contact portion of the springs is restricted by the hight of a housing 11, spring 16 also does not provide adequate spring deflection.
In both of the above prior art connectors, the spring action is relatively large because of the proximity of the pivot positions to the contact portions. Spring action increases as the closer the contact portion is a pivot point. More force is then required to insert the printed circuit board into the connector. This results in increased wear of the surfaces of the printed circuit board with each insertion of the board into the connector. These connectors do not therefore provide a sufficiently stable contact force.